||In this review, therefore, we summarize and discuss critically the current state of epidemiologic knowledge and the strengths and weaknesses of the available evidence on the relation of EMF exposure in man to risk of cancer and other adverse outcomes. We have taken EMF to refer to time-varying electric and/or magnetic fields <300 Hz. Where studies have specifically measured electric and/or magnetic fields, we have indicated the type of field; where they have not, or where it is not clear from the report, we have referred to EMF generically. We have restricted our attention to epidemiology, not experimental human studies; and although we have referred to some research on physiological effects, these are not reviewed systematically, and the review is primarily concerned with pathological end points. Particular attention is paid to methodological issues and to exposure measures because these have been a contentious and difficult area of EMF research and are critical to appraisal of the existing literature. Finally, we comment on areas where further research is needed.